1. Field of the Invention
The present invention generally relates to devices for the delivery of powdered materials from a storage reservoir to a target surface area in the form of an aerosolized powder spray. More specifically, the present invention relates to a convenient, self-contained, single-hand-held, single-hand-operated device for both aerosolizing and delivering powdered materials in the form of a spray so as to substantially evenly coat a target surface area with a desired and/or predetermined quantity of powdered material. Still more particularly, the present invention relates to a device for the application of medicinal materials in powder spray form to selected target surface areas such as areas located in and/or around open or “closed” laparoscopic surgical fields of substantially any size and degree of visibility.
2. Summary of the Prior Art
Most materials may be easily and advantageously manufactured, distributed and stored in powder form. This is significant because the powder form of various materials and/or compositions often can be premixed for future use in a manner such that the resulting mixture evidences minimal component separation problems during storage. Further, the size of the constituent elements (i.e., particles) of a powder mixture can be controlled so as to insure that a substantially homogeneous distribution of a desired concentration of each of those constituent elements is achieved when the powder mixture is spread over a specified area. Indeed, it often has been found to be possible to achieve a more homogenous material distribution on, and more complete material coverage of, a target surface area when the applied materials are in powder form than when those materials are disbursed in the form of liquid droplets entrained in a propellant stream as in a conventional aerosol spray.
Powder delivery devices of numerous forms are known generally in the art. These known devices range from the simple to the complex, and have found use for a broad multiplicity of purposes ranging from the application of industrial coatings to work-pieces, to the application of insecticides both indoors and outdoors, to the marking of boundaries or particularly determined locations, to the delivery of medicinal materials to patients both topically and internally, among very many others.
Perhaps the simplest powder delivery device known is the simple shaker. Shakers typically take the form of containers with holes in their tops that are inverted and shaken to cause a material in powder form stored within the container to be selectively discharged from the container through the holes. For example, shakers are often used in the topical application of powders, such as in the topical application of talcum powder to the surface of the skin. The control of the flow of the powder through the holes of a shaker, however, is not accurate, and the resulting coverage of the desired target surface area is not usually uniform. This is because in use the agglomerated powder in the container is broken up non-uniformly by the abrupt stoppages of the movement of the container at the extremes of the up and down limits of the applied shaking motion, and also because the flow of the non-uniformly broken up powdered material through the holes cannot be accurately controlled.
Another well-known powder delivery device is the so-called “atomizer” often used in the treatment of conditions such as asthma. This type of powder delivery device is easily used, often by untrained individuals, and also typically includes provision for the secure storage of a powdered material to be delivered as well as provision for the generation of a propellant stream within the device, as will be discussed further below.
Still more complex powder delivery devices also are known including, for example, structures designed for the sequential delivery of measured unit doses of powdered materials from the device. Known powder delivery devices of the latter type commonly include at least one internal powder metering chamber from which only single, pre-measured volumes of a powdered material constituting predetermined dosage quantities thereof can be expelled at any one time. These devices also often include provision for the automatic refilling of the powder-metering chamber subsequent to each discharge of the content thereof in use.
In most medical applications, it has been found to be desirable for medicinal powdered materials to be delivered to their target areas in the form of a “soft cloud” in which the particles constituting the powder remain in a visibly separated relationship relative to one another as they travel from the delivery device to the target area. This avoids the infliction of trauma to bodily tissue in the area to be coated by the powder material. However, despite their high cost and the often disadvantageous (or damaging) force of their output sprays, homogeneous spray delivery devices such as closed aerosol cans containing a supply of powdered material and a gas under pressure for discharging a concentrated aerosolized powder stream, are often used for medicinal powdered material delivery. This is primarily because users are generally familiar and comfortable with the operation of common aerosol cans. In addition, the typically single-hand-held, single-hand-operated nature of standard aerosol cans, as well as the substantial reliability of the directionality and homogeneity of the output sprays achieved by standard aerosol cans, are contributing factors to their use as powdered material spray devices despite the drawbacks mentioned above.
As briefly alluded to above, powder materials stored in a container tend to agglomerate into a cohesive mass. This is true whether the container constitutes a part of the powder delivery device or is external to the powder delivery device. Consequently, delivery devices for powdered materials require not only that the powdered material be conveyed in a propellant stream to the target site, but also that preliminarily to its discharge from its storage container (reservoir), the powdered material being transferred to the target site be separated from the remainder of the agglomerated mass of stored powder in the container/reservoir and aerosolized.
The result of the foregoing steps is the creation of a desired powder concentration within a propellant at, or substantially immediately prior to, its discharge from the device toward the target surface area. To accomplish the latter objectives, numerous devices have been suggested in the art for the control of the aerosolization of a powdered material stored in a container as well as for the discharge of an aerosolized powder from a container in a manner calculated to achieve a desired, substantially homogeneous coating of a target surface area.
An example of a device of the latter type is known in connection with the delivery of asthma medication in powdered form. In this case, the interior of the container/reservoir/dosage chamber includes provision both for aerosolizing the stored powder as well as for the projection of the aerosolized powder into the lungs and sinus cavities of the patient so as to substantially homogeneously coat, and thereby treat, the internal bodily tissue making up the patient's respiratory system. Devices of this type, often referred to as “inhalers” or “atomizers”, typically include a gaseous material under artificially created pressure such as an aerosol can or an external pressurized propellant supply that is released into (and from) a powder storage reservoir.
Alternatively, however, a mechanical pump such as a plunger mounted adjacent to a powder containing reservoir also often is used to create a suitable propellant stream. In the latter case, the user forces a gaseous material (typically air) into the reservoir under pressure by the depression of the plunger or a similar mechanical manipulation of the device in a manner that causes a flow of propellant (typically air) to aerosolize at least a predetermined minimum quantity of the stored powder in the reservoir and to discharge substantially all of the so aerosolized powder to a spray head and thence to the surfaces of the patient's respiratory system that are to be treated.
Asthma “inhalers” typically are small devices that fit well in a patient's pocket or purse. Further, they generally are easy to use as well as being single-hand-held and single-hand-operated devices. Nevertheless, the user typically places the discharge orifice of the “inhaler” into his mouth prior to depressing the plunger or otherwise injecting a pressurized gas into the container/reservoir. Hence, without its interaction with the patient's mouth, an “inhaler” type device does not provide an easily manipulated device that is suitable for use in the controlled and accurate delivery of aerosolized powders to target surfaces generally, and particularly is not suited to the delivery of powdered materials for reliable target surface coating into small area surgical sites that are often not readily visible (for example, laparoscopic surgical sites).
The well-known, simple so-called “puffer”, on the other hand, is a device wherein the powder reservoir commonly constitutes, in its simplest form, a container with inwardly deformable sides having both an outlet port and a one-way inlet valve. In this form of powdered material spray device, a quick and forceful inward deformation of the container walls causes a portion of a quantity of powder stored within the container to be aerosolized and thereafter discharged in the form of a “puff” (as in a “puff of smoke”) from the outlet port (i.e., to be separated from the agglomerated stored powder mass and entrained in the gas being discharged from the interior of the container by the quick and forceful inward collapse of its side walls).
Thereafter, the collapsing force on the container walls is released, and the resilient nature of the material of the container tends to cause the container to resume its original shape. As this shape resumption occurs, the partial vacuum created within the container as the walls of the container attempt to expand outwardly to resume their original shape is released by allowing air to enter the container through the one-way valve. Hence, the reversal of the deformation of the container is easily completed. This type of “puffer”, although subject to clogging at its inlet and outlet in a manner similar to the simple shaker, nevertheless has been found to work reasonably well for topical applications of aerosolized powders such as for example to the surface of the skin or within large so-called “open” surgical sites wherein the target surfaces to be coated with the powdered material are both visible and readily accessible. However, in those cases in which the surface to be coated is not visible or otherwise readily accessible, the simple “puffer” and similar powdered material delivery device designs have been found not to be efficiently or satisfactorily workable.
To deal with the foregoing problems inherent in simple powdered material delivery devices, systems have been developed in which propellants are used in connection with extended conduits (i.e., cannulas) to project powder sprays generally, as well as particularly into relatively inaccessible areas of “open” surgical sites, or indeed into relatively inaccessible and invisible locations, such as internal laparoscpic surgical sites. These aerosol spray based systems have the benefit of at least sometimes being single-hand-operable (i.e., in those cases in which one hand of the operator is not required to hold and operate the propellant source while his other hand controls the direction of the spray).
An example of one such system, generally and illustratively shown in FIG. 1, includes a conventional aerosol propellant can 2 having the exit portal of its aerosol release valve 4 extended via a cannula or other form of conduit 6 so as to allow an output of aerosolized powdered material to be more accurately directed and/or concentrated.
Devices/systems of this type, while sometimes useful for the spraying of topical powdered materials in generally open settings, have proven to be unsatisfactory when the target surfaces are located in confined volumes in which a so-called “soft cloud” spray is desired and/or necessary. Accordingly, particularly for the spraying of medicinal powders so as to homogeneously coat small (and/or confined) internal operative sites without the infliction of damaging trauma to the target tissue conventional aerosol propellant can type devices are contra-indicated. This is because factors such as (i) air leakage at the can/valve interface and/or point of attachment of the valve to the spray directing extension member, (ii) the inability satisfactorily to control the velocity of high-pressure aerosolized powder sprays generated by typical aerosol can valves, and (iii) the well known inability of typical aerosol cans to reliably discharge homogeneous sprays when spatially oriented in inverted positions with their release valves disposed below the horizontal, among other factors, all significantly tend to reduce both the reliability and the medical functionality of the conventional aerosol can form of powder sprayer.
The system currently most favored in the art for surgical/laparoscopic medicinal powder spraying utilizes the so-called “Wolf” sprayer as generally and illustratively depicted in FIGS. 2 and 3. This system, generally indicated at 8, includes a propellant source such as a source of pressurized gas (represented by a closed can 18, but permissibly including connection to an external compressor, for example via a wall fitting provided in an operating room) provided with the capability of discharging a pressurized gas in the form of discrete pulses, see element 12 (FIG. 2), or alternatively, a hand pump such as that generally indicated at 10 (FIG. 3). The hand pump 10 ideally is operated by the exertion of quick, forceful pressure against a deformable portion 14 so as to expel the air content of the pump through a discharge tube 16 in the form of a gas pulse.
The metered pulse source of pressurized gas 12, on the other hand, is more complex. In particular, it generally includes the propellant source 18 connected to a valve 20 by a conduit 22. Further, the valve 20 is constructed so as to periodically alternately open and close thereby permitting the controlled discharge of uniform gas pulses into a discharge tube 24. More specifically, a metered quantity (pulse) of propellant under controlled maximum pressure is introduced into the conduit 22 for release by the valve 20 in the form of a gas pulse of predetermined size and pressure similar to that achievable with the hand pump 10 shown in FIG. 2. Of course, the structure depicted in FIG. 2 is superior to that of FIG. 3 in terms of its control of the size and pressure of the pulse and hence also in terms of the powder dosage that will eventually be carried to the target surface area of the patient. On the other hand, however, the structure depicted in FIG. 3 provides greater versatility than that of FIG. 2 due to the less complex nature of the pulse creation means, and the fact that it is not tied to an expensive and/or fixed pressurized gas source.
As will appear more fully below, however, both of these propellant sources are cumbersome, expensive and at least somewhat complex. Further, the systems of which those propellant sources form a part are further limited by the required substantially vertical spatial disposition of their Wolf-type powder reservoir in a manner that renders single-hand-held operation of the device substantially impractical, if not impossible.
In addition, it is to be recognized that particularly in the case of delicate surgical procedures involving delicate tissue structures, there is a tendency for a user to be at least somewhat tentative in the application of the aerosolized powder to the target surface. Accordingly, it can be expected that the deflation forces sequentially applied by such a user to the flexible portion 14 of the pump 10 often will be such that the flexible portion 14 is not fully deflated by each applied force imparted to it by the user. In devices/systems such as that depicted in FIG. 3, this often results in the unsatisfactory operation of the remainder of the device.
Therefore, it will be understood by those skilled in the art that in the devices depicted in FIGS. 2 and 3 the respective conduits 16, 24 input gas pulses such as those discussed above into an aerosolizing device (commonly designated as a so-called “Wolf Sprayer”) shown generally at 26. This aerosolizing device 26 includes a reservoir portion 28 having the general form of a test tube (i.e., an elongate substantially cylindrical portion 30 having a generally hemispherical closed end 32), and a cover member generally indicated at 34.
The cover member 34 defines an input conduit 36 that extends from a fitting 38 outside of the cover member through the cover to an elongate section 40 that extends almost to the closed end 32 of the reservoir portion generally parallel to the longitudinal axis of the reservoir. The cover member 34 also defines an output conduit 42 that extends from a fitting 44 through the cover member to a section 46 substantially shorter than the elongate section 40 of the conduit 36 that also extends into the reservoir substantially parallel to the longitudinal axis of the reservoir. Of course, it will be understood that the cover member 34 is generally substantially more complex than is illustratively shown in FIGS. 2 and 3. For example, a lower portion of the cover is commonly screwed or otherwise secured in removable sealed relation to a top portion thereof. This allows the reservoir to be slid through the lower portion such that an outwardly extending flange at its open end (not specifically shown) engages an inwardly extending flange at the bottom of the lower cover portion (also not specifically shown). Thus, the reservoir may be filled, refilled and/or replaced only by the cumbersome and inconvenient disassembly of the cover and the removal of the reservoir therefrom. In addition, these complexities in the construction of the cover also create a potential for gas leakage at the connection of the lower and top portions of the cover member. Further, they introduce serious problems in the accomplishment of the satisfactory sterilization the components of the device and its content prior to their use in and/or near open surgical fields.
Finally, a flexible or rigid conduit 48 extends from the output fitting 44 of the cap member 34 to a spray head generally indicated at 50.
With this system, as generally indicated by the arrows depicted within the reservoir 28, a gas pulse from the propellant source is introduced into a quantity of powder generally indicated at 52 stored in the portion of the reservoir 28 adjacent to its closed end through the input conduit 36 (assuming that the open end of the elongate section 40 of the input conduit 36 has not been clogged by agglomerated powdered material located in the reservoir at the time of its original insertion into the reservoir 28 during the assembly of the cap to the reservoir as generally discussed above).
The gas pulse mixes with the powder stored in the reservoir in a sort of swirling motion adjacent to the closed end 32 of the reservoir 28 (see representative arrows in the reservoir) thereby aerosolizing at least some of the stored powder into the open head space located between the top of the stored powder mass and the cover (i.e., to entrain some of the powdered material in the pressurized gas located in the open head space between the surface of the agglomerated powdered material in the bottom of the reservoir and the open top thereof that is sealed by the cover member) in the form of a cloud of separate powdered material particles. Concurrently, the increased pressure introduced into the reservoir by the input propellant pulse forces at least part (usually a major portion) of the aerosolized powder in the head space of the reservoir out of the reservoir and through the cover member via the open end of the output conduit 42 located within the head space of the reservoir, and thence to the spray head 50.
Accordingly, it will be understood that the tentative operation of the hand pump mentioned above often is insufficient to generate a gas pulse of adequate duration and pressure to cause the operation of the device just discussed to occur, or if that operation does occur, to cause it to occur in a satisfactory manner. Similarly, while less likely, the partial release of a pressurized gas pulse in the structure depicted in FIG. 2 due to the tentative actuation of the release valve also can cause insufficient aerosolization and discharge of powdered material.
These results can be very problematic because, as mentioned briefly above, there is a natural tendency for individuals performing close, delicate and complex tasks to do so utilizing small movements so as to maintain better control over the effects of their actions. Consequently, it will be understood that the preferred manner of operating the currently preferred devices is counterintuitive to this natural tendency of operators such as those in the surgical field with results that are at best less than optimum quantities of powdered material spray impinging upon the target surface area.
Furthermore, also as briefly mentioned above, the currently preferred powdered material delivery systems depicted in FIGS. 2 and 3 are cumbersome, expensive and essentially impossible to operate with one hand regardless of whether a pump 10 or a metered propellant source 12, is used. Instead, it has been found that the propellant source typically must be operated with one hand while the other hand of the operator controls the spray head so as to direct the output powdered material spray to the desired target surface areas.
Still further, also as briefly mentioned above, it will be understood that in the currently preferred devices, the longitudinal axis of the reservoir must be maintained in a substantially vertical spatial position in order to ensure that the powder stored therein is aerosolized in the desired manner. As is readily apparent from the drawings (FIGS. 2 and 3), the further the reservoir is tilted from the vertical, the smaller the affect the input propellant pulses will have on the stored, agglomerated powder, particularly as the quantity of powdered material in the reservoir is used up (i.e., discharged from the sprayer). This is most significantly the case when the top of the reservoir is tilted to the right as depicted in FIGS. 2 and 3 because in that event the surface of the powder stored in the reservoir tends to tilt at an angle to the longitudinal axis of the reservoir rather than being located substantially normal thereto. This results in the surface of the stored powdered material approaching the outlet of the aerosolizing pulses into the reservoir thereby reducing the mixing action of input propellant pulses within the agglomerated powder stored in the reservoir (and indeed, possibly clogging the opening of the output conduit located within the reservoir).
Hence, the further from the vertical the longitudinal axis of the reservoir in a so-called “Wolf” sprayer is tilted, the smaller the control that can be exerted upon the quantity of powder aerosolized by each propellant pulse (assuming no clogging and the adequacy of the pressure contained in each pulse). In other words, the tilting of the reservoir skews the disposition of the powder stored in the reservoir in a manner that changes the quantity of the stored powder directly impacted by the input propellant pulses within the body of the stored powder (see arrows depicting propellant flow within the reservoir shown in FIGS. 2 and 3). Therefore, tilting of the reservoir reduces the control of the powder dose aerosolized by each pulse because less powder is influenced by the full impact of the propellant pulse thereby placing significant constraints upon the manner in which the system is required to be used.
In addition, since the cross-section of the output conduit is limited, the quantity of aerosolized powder that can be delivered by each propellant pulse also is limited. Still further, it has been found to be difficult to ensure that all of the powder stored in the reservoir can be delivered satisfactorily by the devices generally depicted in FIGS. 2 and 3. This adversely affects the efficiency of powdered material use. Consequently, inefficient overfilling, refilling and/or a switch to a new device prior to the use of all of the stored powder in a particular reservoir all have been found to be necessary operational drawbacks encountered in the use of the currently preferred system for the delivery of medicinal powders to and in the vicinity of surgical sites.
In summary, therefore, the currently preferred concept for the generation and spray of powdered materials is cumbersome in structure and typically requires two-handed operation by the user thereby preventing the user from performing other tasks with one of his hands. Also, the various components of the device are not easily sterilized, yet they are designed for reuse rather than being single-use disposable devices. These are important disadvantages, particularly in a surgical setting in which the available space for each surgeon or technician to perform is limited yet the efficiency with which all surgical tasks can be performed within the available area is significant.